Ah, sorry. Consider my view changed on the labour bit. I know what peristalsis is in the digestive system, I don't want to imagine what peristalsis refers to in the uterine/reproductive system.

Anyway, my post was sparked by a comment from a female doctor to a poster in the lactose intolerance sub:

I described my symptoms (years ago) to my doctor, who was a woman, and she said "you are one of the few men who knows what a period feels like". r/kanehau

I totally misread his post and thought the doctor had said contractions. I then added the period bit. I have read severally the period comparisons on this very sub.

Edit: crossposting my response to his comment:

I have IBS as well. I'm a 6'4" dad and I've been on all fours on my bed at 2AM doing lamaze breathing. And it comes in waves, and I then assume the position and start the lamaze breathing, before collapsing in a sweaty heap and awaiting the next round. I do not know how I found it out it but deep, measured breathing is far more effective at riding out the cramps than my previous response of closing my eyes, holding my breath, staying super-silent, and contracting every possible muscle in my body. Now I just look and sound like a prize heifer in labour, and it's so much better. Full disclosure: I used to think I'd discovered something new until I connected the dots.